package com.htu.mapreduce;
import java.io.IOException;
import java.util.Iterator;
import org.apache.hadoop.conf.Configuration;
import org.apache.hadoop.fs.Path;
import org.apache.hadoop.io.Text;
import org.apache.hadoop.mapreduce.Job;
import org.apache.hadoop.mapreduce.Mapper;
import org.apache.hadoop.mapreduce.Reducer;
import org.apache.hadoop.mapreduce.lib.input.FileInputFormat;
import org.apache.hadoop.mapreduce.lib.output.FileOutputFormat;
public class DanJoin {
    public static class Map extends Mapper < Object, Text, Text, Text > {   //实现map函数 
        public void map(Object key, Text value, Context context)
        throws IOException,
        InterruptedException {
            String line = value.toString();
            String[] arr = line.split(" ");//按行截取
            String mapkey = arr[0];
            String mapvalue = arr[1];
            String relationtype = new String();//左右表标识
            relationtype = "1";
            context.write(new Text(mapkey), new Text(relationtype + "+" + mapvalue));
            //System.out.println(relationtype+"+"+mapvalue);  
            relationtype = "2";
            context.write(new Text(mapvalue), new Text(relationtype + "+" + mapkey));
            //System.out.println(relationtype+"+"+mapvalue);  
        }
    }
    public static class Reduce extends Reducer < Text, Text, Text, Text > {
        public void reduce(Text key, Iterable < Text > values, Context context)
        throws IOException,
        InterruptedException {
            int buyernum = 0;
            String[] buyer = new String[20];
            int friendsnum = 0;
            String[] friends = new String[20];
            Iterator ite = values.iterator();
            while (ite.hasNext()) {
                String record = ite.next().toString();
                int len = record.length();
                int i = 2;
                if (0 == len) {
                    continue;
                }
                char relationtype = record.charAt(0);
                if ('1' == relationtype) {
                    buyer[buyernum] = record.substring(i);
                    buyernum++;
                }
                if ('2' == relationtype) {
                    friends[friendsnum] = record.substring(i);
                    friendsnum++;   //buyernum和friendsnum数组求笛卡尔积 
                }
            }
            if (0 != buyernum && 0 != friendsnum) {
                for (int m = 0; m < buyernum; m++) {
                    for (int n = 0; n < friendsnum; n++) {
                        if (buyer[m] != friends[n]) {  //输出结果 
                            context.write(new Text(buyer[m]), new Text(friends[n]));
                        }
                    }
                }
            }
        }
    }
    public static void main(String[] args) throws Exception {

        Configuration conf = new Configuration();
        String[] otherArgs = new String[2];
        otherArgs[0] = "hdfs://localhost:9000/mymapreduce1/in/buyer1";
        otherArgs[1] = "hdfs://localhost:9000/mymapreduce1/out6";
        Job job = new Job(conf, " Table join");
        job.setJarByClass(DanJoin.class);
        job.setMapperClass(Map.class);
        job.setReducerClass(Reduce.class);
        job.setOutputKeyClass(Text.class);
        job.setOutputValueClass(Text.class);
        FileInputFormat.addInputPath(job, new Path(otherArgs[0]));
        FileOutputFormat.setOutputPath(job, new Path(otherArgs[1]));
        System.exit(job.waitForCompletion(true) ? 0 : 1);

    }
}